Demodulation reference signal-assisted listen-before-talk for full-duplex wireless communications in unlicensed spectrum

ABSTRACT

Aspects described herein relate to receiving, from a base station on a first subband of an unlicensed frequency band, control information that includes a resource allocation of an uplink transmission associated with the first UE and a demodulation reference signal (DMRS) configuration of a downlink transmission associated with a second UE. The apparatus also may obtain one or more measurements of a DMRS within channel activity on a second subband of the unlicensed frequency band using a listen-before-talk (LBT) operation based on the DMRS configuration. The apparatus also may determine whether the channel activity corresponds to the downlink transmission associated with the second UE based on the one or more measurements of the DMRS within the channel activity. The apparatus also may communicate, with the base station on the second subband, the uplink transmission when the channel activity corresponds to the downlink transmission associated with the second UE.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 63/088,379, entitled “DEMODULATION REFERENCESIGNAL-ASSISTED LISTEN-BEFORE-TALK FOR FULL-DUPLEX WIRELESSCOMMUNICATIONS IN UNLICENSED SPECTRUM” and filed on Oct. 6, 2020, whichis expressly incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates generally to communication systems, andmore particularly, to Demodulation Reference Signal (DMRS)-assistedListen-Before-Talk (LBT) for full-duplex wireless communications inunlicensed spectrum.

INTRODUCTION

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable low latency communications (URLLC). Some aspects of 5G NRmay be based on the 4G Long Term Evolution (LTE) standard. Aspects ofwireless communication may comprise direct communication betweendevices, such as based on sidelink. There exists a need for furtherimprovements in sidelink communication technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

In some wireless communication technologies, a user equipment (UE)and/or an base station can be configured for full duplex (FD)communications where the UE and/or base station can concurrentlytransmit and receive over wireless communication resources within thesame frequency band or the same component carrier.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

A base station can be capable of full-duplex communications intransmitting downlink signaling to a first UE while concurrentlyreceiving uplink transmission from a second UE. The base station mayoperate in a full-duplex mode, where the base station may transmitdownlink signaling to the first UE and at the same time wants to servethe second UE with an uplink transmission. The second UE may receivedownlink control information that schedules the uplink transmission. Thesecond UE may perform a listen-before-talk (LBT) operation, or otherchannel assessment procedure for acquiring a channel, prior to theuplink scheduling grant and detect any channel activity that may causethe second UE to drop or delay the uplink transmission. However, thechannel activity may include other inter-cell downlink transmissionsoccupying the same band that can cause the second UE to drop or delaythe uplink transmission.

The present disclosure provides for a DMRS-assisted LBT operation thatuses a DMRS of the downlink signaling by an uplink scheduled UE todetermine channel availability during a downlink transmission to anotherUE. If the uplink scheduled UE can distinguish between the base stationdownlink signaling and the inter-cell downlink transmissions or othertechnologies occupying the same band, then the uplink scheduled UE cantransmit the uplink signal without wasting resources. The subjecttechnology can help improve the performance of uplink communications andincrease the utilization of resources in an efficient manner.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus is configured to receiving,from a base station on a first subband of an unlicensed frequency band,control information comprising a resource allocation of an uplinktransmission associated with the first UE and a demodulation referencesignal (DMRS) configuration of a downlink transmission associated with asecond UE. The apparatus is also configured to obtain one or moremeasurements of a DMRS within channel activity on a second subband ofthe unlicensed frequency band using a listen-before-talk (LBT) operationbased on the DMRS configuration. The apparatus is also configured tocommunicate, with the base station on the second subband, the uplinktransmission when the channel activity corresponds to the downlinktransmission associated with the second UE based on the one or moremeasurements of the DMRS within the channel activity.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus are provided. The apparatus is configured togenerate control information comprising a resource allocation of anuplink transmission associated with a first user equipment (UE) and ademodulation reference signal (DMRS) configuration of a downlinktransmission associated with a second UE. The apparatus is alsoconfigured to transmit, to the first UE on a first subband of anunlicensed frequency band, the control information. The apparatus isalso configured to receive, from the first UE on the second subband, theuplink transmission based on the DMRS configuration and a correspondencebetween channel activity on the second subband and the downlinktransmission associated with the second UE.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a first5G/NR frame, DL channels within a 5G/NR subframe, a second 5G/NR frame,and UL channels within a 5G/NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIGS. 4A and 4B are diagrams illustrating a full-duplex wirelesscommunication environment and communication flow timeline, in accordancewith various aspects of the present disclosure.

FIG. 5 is a diagram illustrating an example of a timeline in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure.

FIG. 6 is a diagram illustrating another example of a timeline in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure.

FIG. 7 is a diagram illustrating an example of a timeline in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure.

FIG. 8 is a diagram illustrating another example of a timeline in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure.

FIG. 9 is a flow chart illustrating an example of a process forDMRS-assisted LBT for full-duplex wireless communications at a userequipment, in accordance with various aspects of the present disclosure.

FIG. 10 is a conceptual data flow diagram illustrating the data flowbetween different components in an example apparatus in accordance withsome aspects of the present disclosure.

FIG. 11 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system inaccordance with some aspects of the present disclosure.

FIG. 12 is a flow chart illustrating an example of a process forDMRS-assisted LBT for full-duplex wireless communications at a basestation, in accordance with various aspects of the present disclosure.

FIG. 13 is a conceptual data flow diagram illustrating the data flowbetween different components in an example apparatus in accordance withsome aspects of the present disclosure.

FIG. 14 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system inaccordance with some aspects of the present disclosure.

DETAILED DESCRIPTION

The described features generally relate to scheduling devices tocommunicate with a base station capable of full duplex (FD)communications. FD communications, as referred to herein, can include asingle node (e.g., a user equipment (UE) or access point) transmittingand receiving (e.g., concurrently) over communication resources in thesame frequency band and/or over communication resources in the samecomponent carrier (CC). In one aspect, FD communications can includein-band full duplex (IBFD) where the single node can transmit andreceive on the same time and frequency resource, and the downlink anduplink can share the same IBFD time/frequency resources (e.g., fulland/or partial overlap). In another aspect, FD communications caninclude sub-band FD (also referred to as “flexible duplex”) where thesingle node can transmit and receive at the same time but on differentfrequency resources within the same frequency band (or overcommunication resources in the same CC), where the downlink resource andthe uplink resources can be separated in the frequency domain (e.g., bya guard band). In an aspect, the guard band in sub-band FD can be on theorder of resource block (RB) widths (e.g., 180 kilohertz (KHz) for thirdgeneration partnership project (3GPP) long term evolution (LTE) andfifth generation (5G) new radio (NR), 360 and 720 KHz for NR, etc.).This can be distinguished from a guard band in frequency divisionduplexing (FDD) communications defined in LTE and NR, which can be 5megahertz (MHz) or more, and the associated resources in FDD are definedbetween frequency bands, but not within the same frequency band (orresources in the same CC) as is the case in sub-band FD communications.

In addition, for example, the UE and base station can communicate in anunlicensed frequency spectrum, such that the UE and base station canacquire a communication medium before transmitting uplinkcommunications. For example, acquiring the communication medium caninclude acquiring a channel (e.g., a frequency range corresponding to aE-UTRA Absolute Radio Frequency Channel Number (EARFCN)) by performing alisten-before-talk (LBT) operation or other clear channel assessment(CCA) operation to ensure the channel is free for transmission beforecommunicating over the channel. In some aspects, the LBT operation isused for competitive resolution of access to shared frequency resourcesin a licensed or unlicensed frequency spectrum. The LBT operation mayinclude performing a CCA procedure to determine whether a shared channelis available. The UE may monitor a frequency and determine whether othertransmissions are occurring on that frequency. When it is determinedthat a shared channel is available, the device may send a signal toreserve the channel prior to data transmission. Other devices maymonitor the reservation signal to detect transmissions and may useenergy detection to monitor the shared channel to determine whether theshared channel is busy or free.

Where a base station is operating in a full-duplex mode, the basestation can transmit a downlink (DL) signal to a first user equipment(UE) and at the same time can serve a second UE allowing the second UEto transmit a physical uplink shared channel (PUSCH) transmission. Inthis regard, for example, the second UE can receive downlink controlinformation (DCI) in a downlink control channel (e.g., physical downlinkcontrol channel (PDCCH)) scheduling the PUSCH transmission. The secondUE can then perform LBT before the PUSCH grant to determine if thecommunication medium is free before transmitting over the resources ofthe PUSCH grant. In this example, however, as the base station istransmitting to the first UE, the second UE may find activity on thecommunication medium (e.g., channel) which may lead failure of the LBTbefore the PUSCH resources and thus the second UE may drop or delay thePUSCH transmission. As the base station is capable of full-duplex,however, the base station can receive the PUSCH transmission from thesecond UE while transmitting the DL signal to the first UE.

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an Evolved Packet Core (EPC) 160, and anothercore network 190 (e.g., a 5G Core (5GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells(low power cellular base station). The macrocells include base stations.The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to asEvolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN)) may interface with the EPC 160 throughbackhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as Next Generation RAN(NG-RAN)) may interface with core network 190 through backhaul links184. In addition to other functions, the base stations 102 may performone or more of the following functions: transfer of user data, radiochannel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over backhaul links 134 (e.g., X2interface). The backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, FlashLinQ, WiMedia,Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include an eNB, gNodeB (gNB), or another typeof base station. Some base stations, such as gNB 180 may operate in atraditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies,and/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz) hasextremely high path loss and a short range. The mmW base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the extremelyhigh path loss and short range.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMES 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MIME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include a Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides QoS flow andsession management. All user Internet protocol (IP) packets aretransferred through the UPF 195. The UPF 195 provides UE IP addressallocation as well as other functions. The UPF 195 is connected to theIP Services 197. The IP Services 197 may include the Internet, anintranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service,and/or other IP services.

The base station may also be referred to as a gNB, Node B, evolved NodeB (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a transmit reception point(TRP), or some other suitable terminology. The base station 102 providesan access point to the EPC 160 or core network 190 for a UE 104.Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, a tablet, a smart device, a wearable device, avehicle, an electric meter, a gas pump, a large or small kitchenappliance, a healthcare device, an implant, a sensor/actuator, adisplay, or any other similar functioning device. Some of the UEs 104may be referred to as IoT devices (e.g., parking meter, gas pump,toaster, vehicles, heart monitor, etc.). The UE 104 may also be referredto as a station, a mobile station, a subscriber station, a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

Referring again to FIG. 1, in certain aspects, the UE 104 may beconfigured to perform DMRS-assisted LBT operations for full-duplexwireless communications in an unlicensed spectrum. For example, the UE104 of FIG. 1 may include a channel sensing component 198 configured toreceive, from a base station on a first subband of an unlicensedfrequency band, in which the control information includes a resourceallocation of an uplink transmission associated with the first UE and aDMRS configuration of a downlink transmission associated with a secondUE. The UE 104 may obtain one or more measurements of a DMRS withinchannel activity on a second subband of the unlicensed frequency bandusing an LBT operation based on the DMRS configuration. The UE 104 maydetermine whether the channel activity corresponds to the downlinktransmission associated with the second UE based on the one or moremeasurements of the DMRS within the channel activity. The UE 104 maycommunicate, with the base station on the second subband, the uplinktransmission when the channel activity corresponds to the downlinktransmission associated with the second UE.

Referring again to FIG. 1, in certain aspects, the base station 102/180may be configured to provide a DMRS configuration to facilitate theDMRS-assisted LBT operations in full-duplex wireless communications overan unlicensed spectrum. For example, the base station 102/180 of FIG. 1may include a configuration component 199 configured to generate controlinformation comprising a resource allocation of an uplink transmissionassociated with a first UE and a DMRS configuration of a downlinktransmission associated with a second UE. The base station 102/180 maytransmit, to the first UE on a first subband of an unlicensed frequencyband, the control information. The base station 102/180 also mayreceive, from the first UE on the second subband, the uplinktransmission based on the DMRS configuration and a correspondencebetween channel activity on the second subband and the downlinktransmission associated with the second UE.

Although the following description may be focused on 5G NR, the conceptsdescribed herein may be applicable to other similar areas, such as LTE,LTE-A, CDMA, GSM, and other wireless technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G/NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G/NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G/NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G/NR subframe. The 5G/NR frame structure may be FDDin which for a particular set of subcarriers (carrier system bandwidth),subframes within the set of subcarriers are dedicated for either DL orUL, or may be TDD in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G/NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and X isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different framestructure and/or different channels. A frame (10 ms) may be divided into10 equally sized subframes (1 ms). Each subframe may include one or moretime slots. Subframes may also include mini-slots, which may include 7,4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on theslot configuration. For slot configuration 0, each slot may include 14symbols, and for slot configuration 1, each slot may include 7 symbols.The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Thesymbols on UL may be CP-OFDM symbols (for high throughput scenarios) ordiscrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (alsoreferred to as single carrier frequency-division multiple access(SC-FDMA) symbols) (for power limited scenarios; limited to a singlestream transmission). The number of slots within a subframe is based onthe slot configuration and the numerology. For slot configuration 0,different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots,respectively, per subframe. For slot configuration 1, differentnumerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, persubframe. Accordingly, for slot configuration 0 and numerology μ, thereare 14 symbols/slot and 2^(μ) slots/subframe. The subcarrier spacing andsymbol length/duration are a function of the numerology. The subcarrierspacing may be equal to 2^(μ)*15 kKz, where μ is the numerology 0 to 5.As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and thenumerology μ=5 has a subcarrier spacing of 480 kHz. The symbollength/duration is inversely related to the subcarrier spacing. FIGS.2A-2D provide an example of slot configuration 0 with 14 symbols perslot and numerology μ=0 with 1 slot per subframe. The subcarrier spacingis 15 kHz and symbol duration is approximately 66.7 μs.

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R_(x) for one particular configuration, where 100× is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A primary synchronization signal (PSS) may be within symbol2 of particular subframes of a frame. The PSS is used by a UE 104 todetermine subframe/symbol timing and a physical layer identity. Asecondary synchronization signal (SSS) may be within symbol 4 ofparticular subframes of a frame. The SSS is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DM-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSS and SSS to form a synchronization signal (SS)/PBCH block. TheMIB provides a number of RBs in the system bandwidth and a system framenumber (SFN). The physical downlink shared channel (PDSCH) carries userdata, broadcast system information not transmitted through the PBCH suchas system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. Although not shown, the UE may transmitsounding reference signals (SRS). The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. ThePUSCH carries data, and may additionally be used to carry a bufferstatus report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with the channel sensing component 198 of FIG. 1.

At least one of the TX processor 316, the RX processor 370, and thecontroller/processor 375 may be configured to perform aspects inconnection with the configuration component 199 of FIG. 1.

FIG. 4A illustrates an example of a wireless communication environment400, where a base station 102/180 can be capable of full-duplexcommunications in transmitting downlink signaling to a first UE 104(e.g., UE1) while concurrently receiving uplink transmission from asecond UE 106 (e.g., UE2). As illustrated in FIG. 4A, the base stationmay operate in a full-duplex mode. The base station 102/180 may transmitthe downlink signaling to UE1 and at the same time wants to serve UE2with a PUSCH transmission. The UE2 may receive the PDCCH schedulingPUSCH. The UE2 may perform an LBT operation prior to the PUSCH grant anddetect any channel activity that may cause UE2 to drop or delay thePUSCH transmission.

FIG. 4B illustrates an example of a timeline 450 for communicationsbetween a base station (e.g., BS 102/180) and a first UE (UE1) andbetween the base station and a second UE (UE2). In timeline 450, thebase station can transmit a PDCCH 452 to UE2 indicating resources forUE2 to transmit PUSCH 454. The base station also can transmit a PDSCH406 to UE1 that at least partially overlaps PUSCH 454 in time and/orfrequency, such that when UE2 performs an LBT operation for transmittingPUSCH 454, UE2 may sense signal energy from the base stationtransmitting PDSCH 456. Because the base station is full-duplex capable,the base station may be able to receive PUSCH 454 while transmittingPDSCH 456, and thus the signal energy from PDSCH 456 detected during theLBT operation for PUSCH 454 may not prohibit the PUSCH 454 transmission.However, the channel activity may include other inter-cell downlinktransmissions occupying the same band that may cause UE2 to drop ordelay the PUSCH transmission. Some examples of other inter-cell downlinktransmissions may include downlink transmissions associated with otherradio access technologies (e.g., WiFi, Bluetooth) or downlinktransmissions associated with other base stations that co-exist withinthe cell coverage. The present disclosure provides for a DMRS-assistedLBT operation that includes utilization of a DMRS of the downlinksignaling by the uplink scheduled UE (e.g., UE2) to determine channelavailability during a downlink transmission. If the uplink scheduled UEcan distinguish between the base station downlink signaling and theinter-cell downlink transmissions or other technologies occupying thesame band, then the uplink scheduled UE can transmit the uplink signalwithout wasting resources.

FIG. 5 is a diagram illustrating an example of a timeline 500 in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure. As depicted in FIG. 5, the timeline 500 illustratescommunications between a base station (e.g., BS 102/180) and a first UE(UE1) and between the base station and a second UE (UE2). In timeline500, the base station can transmit a PDCCH 502 to UE2 indicatingresources for UE2 to transmit PUSCH 504. For example, the PDCCH 502 mayinclude control information that includes a resource allocation of thePUSCH 504. The base station also can transmit a PDSCH 506 to UE1 that atleast partially overlaps PUSCH 504 in time and/or frequency.

In some aspects, the control information includes an indication ofexistence or non-existence of the downlink transmission associated withthe second UE at least partially overlapping resources of the uplinktransmission associated with the first UE in one or more of time orfrequency. In various aspects, the control information includes a DMRSconfiguration of the PDSCH 506. The DMRS configuration may include oneor more of a location of a DMRS 510 in time and frequency, a precoderassociated with the DMRS 510, and/or a transmission power of the DMRS510 in the PDSCH 506. In some aspects, the BS 102/180 may determinewhether the PDSCH 506 overlaps the PUSCH 504. The BS may select a firstPDCCH of a plurality of PDCCHs, multiplexed in time or frequency of asubband in the unlicensed spectrum, for transmission of the controlinformation when the PDSCH 506 overlaps the PUSCH 504.

In some implementations, the UE2 performs an LBT operation 508 fortransmitting PUSCH 504. The UE2 may sense signal energy from the basestation transmitting PDSCH 506. For example, the UE2 may obtain one ormore measurements of the DMRS 510 within the sensed channel activityoccupying the same band as the PUSCH 504 based on the DMRSconfiguration. In some aspects, the LBT operation 508 may be performedimmediately prior to the transmission of the PUSCH 504. In otheraspects, the LBT operation 508 may be performed at a predetermined timeprior to the transmission of the PUSCH 504. Although FIG. 5 illustratesthe LBT operation 508 occurring during a symbol duration of the DMRS510, the LBT operation 508 may occur at other times that non-overlapwith the DMRS 510 symbol duration.

The UE2 may determine whether the channel activity corresponds to thePDSCH 506 based on the one or more measurements of the DMRS 510 withinthe channel activity. For example, the UE2 may demodulate the a sensedsignal using the DMRS 510 to determine whether the sensed signal is aPDSCH from the BS. In some aspects, the UE2 may determine an amount ofenergy associated with the channel activity and a radio frequencymeasurement of the DMRS 510 within the channel activity. The UE2 maycompare the amount of energy associated with the channel activity to theRF measurement of the DMRS 510 to determine whether the channel activityenergy corresponds to the DMRS measurement. If both measurementscorrespond to one another, then UE2 may transmit the PUSCH 504 (evenduring transmission of the PDSCH 506) without wasting resources. In someexamples, the amount of channel activity energy may be consistent withthe amount of energy of the DMRS.

FIG. 6 is a diagram illustrating another example of a timeline 600 in agroup-based communication flow with DMRS-assisted LBT for full-duplexwireless communications, in accordance with various aspects of thepresent disclosure. As depicted in FIG. 6, the timeline 600 illustratescommunications between a base station (e.g., BS 102/180) and a first UE(UE1) and between the base station and a second UE (UE2). In contrast toFIG. 5, the group-based communication flow illustrated in FIG. 6facilitates a groupcast transmission of a DMRS configuration to UE2 andUE3. In timeline 600, the base station can transmit a PDCCH 602 to UE2indicating resources for UE2 to transmit PUSCH 604. The base stationalso can transmit a PDSCH 406 to UE1 that at least partially overlapsPUSCH 604 in time and/or frequency, such that when UE2 performs an LBToperation for transmitting PUSCH 604, UE2 may sense signal energy fromthe base station transmitting PDSCH 606.

In one or more implementations, the PDSCH 606 may include a plurality ofDMRS symbol durations (e.g., 610, 618). In this regard, the controlinformation may include a first DMRS configuration specifying a firstDMRS symbol duration (e.g., DMRS 610) of the plurality of DMRS symboldurations during which the UE1 may perform a first LBT operation 608 anda second DMRS symbol duration (e.g., DMRS 618) of the plurality of DMRSsymbol durations during which a third UE (e.g., UE3) may perform asecond LBT operation 616. The BS 102/180 may determine whether the PDSCH606 overlaps a plurality of uplink transmissions associated with aplurality of UEs (e.g., PUSCH 604, PUSCH 614). In this regard, the BS102/180 may select a first group common (GC)-PDCCH of a plurality ofGC-PDCCHs for transmission of the control information to the UE2 and UE3when the PDSCH 606 is determined to overlap the PUSCH 604 and the PUSCH614.

In some implementations, the UE2 performs an LBT operation 608 fortransmitting PUSCH 604. The UE2 may sense signal energy from the basestation transmitting PDSCH 606. For example, the UE2 may obtain one ormore measurements of the DMRS 610 within the sensed channel activityoccupying the same band as the PUSCH 604 based on the DMRSconfiguration. In some aspects, the LBT operation 608 may be performedimmediately prior to the transmission of the PUSCH 604. In otheraspects, the LBT operation 608 may be performed at a predetermined timeprior to the transmission of the PUSCH 604. Although FIG. 6 illustratesthe LBT operation 608 occurring during a symbol duration of the DMRS610, the LBT operation 608 may occur at other times that non-overlapwith the DMRS 610 symbol duration.

In some implementations, the UE3 performs an LBT operation 616 fortransmitting PUSCH 614. The UE3 may sense signal energy from the basestation transmitting PDSCH 606. For example, the UE3 may obtain one ormore measurements of the DMRS 618 within the sensed channel activityoccupying the same band as the PUSCH 614 based on the DMRSconfiguration. In some aspects, the LBT operation 616 may be performedimmediately prior to the transmission of the PUSCH 614. In otheraspects, the LBT operation 616 may be performed at a predetermined timeprior to the transmission of the PUSCH 614. Although FIG. 6 illustratesthe LBT operation 616 occurring during a symbol duration of the DMRS618, the LBT operation 616 may occur at other times that non-overlapwith the DMRS 618 symbol duration.

The UE2 may determine whether the channel activity corresponds to thePDSCH 606 based on the one or more measurements of the DMRS 610 withinthe channel activity. In some aspects, the UE2 may determine an amountof energy associated with the channel activity and a radio frequencymeasurement of the DMRS 610 within the channel activity. The UE2 maycompare the amount of energy associated with the channel activity to theRF measurement of the DMRS 610 to determine whether the channel activityenergy corresponds to the DMRS measurement. If both measurementscorrespond to one another, then UE2 may transmit the PUSCH 604 (evenduring transmission of the PDSCH 606) without wasting resources.

The UE3 may determine whether the channel activity corresponds to thePDSCH 606 based on the one or more measurements of the DMRS 618 withinthe channel activity. In some aspects, the UE3 may determine an amountof energy associated with the channel activity and a radio frequencymeasurement of the DMRS 618 within the channel activity. The UE3 maycompare the amount of energy associated with the channel activity to theRF measurement of the DMRS 618 to determine whether the channel activityenergy corresponds to the DMRS measurement. If both measurementscorrespond to one another, then UE3 may transmit the PUSCH 614 (evenduring transmission of the PDSCH 606) without wasting resources.

FIG. 7 is a diagram illustrating an example of a timeline 700 in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure. The communication flow in the timeline 700 includes adropped PUSCH transmission based on sensed channel activity that doesnot correspond solely to a PDSCH transmission originating from the samebase station (intending to receive the PUSCH transmission) but ratherother inter-cell downlink transmissions. As depicted in FIG. 7, thetimeline 700 illustrates communications between a base station (e.g., BS102/180) and a first UE (UE1) and between the base station and a secondUE (UE2). In timeline 700, the base station can transmit a PDCCH 702 toUE2 indicating resources for UE2 to transmit PUSCH 704. The base stationalso can transmit a PDSCH 406 to UE1 that at least partially overlapsPUSCH 704 in time and/or frequency, such that when UE2 performs an LBToperation for transmitting PUSCH 704, UE2 may sense signal energy fromthe base station transmitting PDSCH 706.

In some implementations, the UE2 performs an LBT operation 708 fortransmitting PUSCH 704. The UE2 may sense signal energy from the basestation transmitting PDSCH 706. For example, the UE2 may obtain one ormore measurements of the DMRS 710 within the sensed channel activityoccupying the same band as the PUSCH 704 based on the DMRSconfiguration. In some aspects, the LBT operation 708 may be performedimmediately prior to the transmission of the PUSCH 704. In otheraspects, the LBT operation 708 may be performed at a predetermined timeprior to the transmission of the PUSCH 704. Although FIG. 7 illustratesthe LBT operation 708 occurring during a symbol duration of the DMRS710, the LBT operation 708 may occur at other times that non-overlapwith the DMRS 710 symbol duration.

The UE2 may determine whether the channel activity corresponds to thePDSCH 706 based on the one or more measurements of the DMRS 710 withinthe channel activity. In some aspects, the UE2 may determine an amountof energy associated with the channel activity and a radio frequencymeasurement of the DMRS 710 within the channel activity. The UE2 maycompare the amount of energy associated with the channel activity to theRF measurement of the DMRS 710 to determine whether the channel activityenergy corresponds to the DMRS measurement. In some aspects, the UE2 maydetermine whether the amount of energy associated with the channelactivity exceeds the measurement of the DMRS within the channel activityby a predetermined threshold. As depicted in FIG. 7, the PDSCH 706 andchannel activity 712 may occupy the same band as the PUSCH 704. In someexamples, the channel activity 712 may fully overlap the PDSCH 706 (orthe PDSCH 706 may partially overlap the channel activity 712). In thisregard, the UE2 may determine that the channel activity does notcorrespond to the downlink transmission associated with the second UEbased on a determination that the amount of energy associated with thechannel activity exceeds the measurement of the DMRS within the channelactivity by the predetermined threshold. For example, the obtainedmeasurements include the sensed channel activity energy and the DMRSenergy, of which the sum of the detected energy exceeds the DMRSmeasurement. If the detected channel activity energy does not correspondto the DMRS measurement, then UE2 may refrain from transmitting thePUSCH 704 to avoid interference and/or collision with the PUSCH 704. Asillustrated in FIG. 7, the UE2 may drop the PUSCH 704.

FIG. 8 is a diagram illustrating another example of a timeline 800 in acommunication flow with DMRS-assisted LBT for full-duplex wirelesscommunications, in accordance with various aspects of the presentdisclosure. In contrast to FIG. 7, the communication flow in thetimeline 700 includes a PUSCH transmission based on sensed channelactivity that does correspond to a PDSCH transmission originating fromthe same base station (intending to receive the PUSCH transmission). Asdepicted in FIG. 8, the timeline 800 illustrates communications betweena base station (e.g., BS 102/180) and a first UE (UE1) and between thebase station and a second UE (UE2). In timeline 800, the base stationcan transmit a PDCCH 802 to UE2 indicating resources for UE2 to transmitPUSCH 804. The base station also can transmit a PDSCH 406 to UE1 that atleast partially overlaps PUSCH 804 in time and/or frequency, such thatwhen UE2 performs an LBT operation for transmitting PUSCH 804, UE2 maysense signal energy from the base station transmitting PDSCH 806.

In some implementations, the UE2 performs an LBT operation 808 fortransmitting PUSCH 804. The UE2 may sense signal energy from the basestation transmitting PDSCH 806. For example, the UE2 may obtain one ormore measurements of the DMRS 810 within the sensed channel activityoccupying the same band as the PUSCH 804 based on the DMRSconfiguration. In some aspects, the LBT operation 808 may be performedimmediately prior to the transmission of the PUSCH 804. In otheraspects, the LBT operation 808 may be performed at a predetermined timeprior to the transmission of the PUSCH 804. Although FIG. 8 illustratesthe LBT operation 808 occurring during a symbol duration of the DMRS810, the LBT operation 808 may occur at other times that non-overlapwith the DMRS 810 symbol duration.

The UE2 may determine whether the channel activity corresponds to thePDSCH 806 based on the one or more measurements of the DMRS 810 withinthe channel activity. In some aspects, the UE2 may determine an amountof energy associated with the channel activity and a radio frequencymeasurement of the DMRS 810 within the channel activity. The UE2 maycompare the amount of energy associated with the channel activity to theRF measurement of the DMRS 810 to determine whether the channel activityenergy corresponds to the DMRS measurement. In some aspects, the UE2 maydetermine whether the amount of energy associated with the channelactivity exceeds the measurement of the DMRS within the channel activityby a predetermined threshold. As depicted in FIG. 8, the PDSCH 806 andchannel activity 812 may partially occupy the same band as the PUSCH804, however, the communication medium is available during most symboldurations of the PUSCH 804 scheduled transmission. In some examples, thechannel activity 812 may partially overlap the PDSCH 806 (or the PDSCH806 may partially overlap the channel activity 812). In this regard, theUE2 may determine that the channel activity corresponds to the downlinktransmission associated with the second UE based on a determination thatthe amount of energy associated with the channel activity does notexceed the measurement of the DMRS within the channel activity by thepredetermined threshold. In some aspects, the UE2 may infer that thechannel activity energy corresponds to the DMRS measurement. If bothmeasurements correspond to one another, then UE2 may transmit the PUSCH804 (even during transmission of the PDSCH 806) without wastingresources.

FIG. 9 is a flow chart illustrating an example of a process 900 forDMRS-assisted LBT for full-duplex wireless communications at a userequipment, in accordance with various aspects of the present disclosure.The process 900 may be performed by a user equipment or a component of auser equipment (e.g., the UE 104, 350, which may include the memory 360and which may be the entire UE 350 or a component of the UE 350, such asthe TX processor 368, the RX processor 356, and/or thecontroller/processor 359). According to various aspects, one or more ofthe illustrated operations of the process 900 may be omitted,transposed, and/or contemporaneously performed.

At 902, a first UE may receive, from the base station on a first subbandof an unlicensed frequency band, control information comprising aresource allocation of an uplink transmission associated with the firstUE and a demodulation reference signal (DMRS) configuration of adownlink transmission associated with a second UE. In some aspects, theDMRS configuration includes one or more of a location of the DMRS intime and frequency, a precoder associated with the DMRS, or atransmission power of the DMRS in the downlink transmission. Forexample, 902 may be performed by reception component 1004 of FIG. 10. Inthe context of FIGS. 1 and 3, for example, the UE 104/350 may receivethe control information. In some aspects, the first UE may determinethat the uplink transmission is scheduled during a same time andfrequency resource as the downlink transmission associated with thesecond UE based on the resource allocation and the DMRS configuration.The first UE may obtain information of the DMRS that indicates one ormore of a location of the DMRS in time and frequency, a precoderassociated with the DMRS or a transmission power of the DMRS in thedownlink transmission.

At 904, the first UE may obtain one or more measurements of a DMRSwithin channel activity on a second subband of the unlicensed frequencyband using an LBT operation based on the DMRS configuration. Forexample, 904 may be performed by LBT component 1008 of FIG. 10. In thecontext of FIGS. 1 and 3, for example, the UE 104/350 may obtain the oneor more measurements of the DMRS. In some aspects, the first UE maydetermine an amount of energy associated with the channel activity and ameasurement of the DMRS within the channel activity.

At 906, the first UE may determine whether the channel activitycorresponds to the downlink transmission associated with the second UEbased on the one or more measurements of the DMRS within the channelactivity. For example, 906 may be performed by determination component1010 of FIG. 10. In the context of FIGS. 1 and 3, for example, the UE104/350 may determine whether the channel activity corresponds to thedownlink transmission.

At 908, the first UE performs the comparison operation. If the channelactivity is determined to correspond to the downlink transmission, thenthe process 900 proceeds to block 910. Otherwise, the process 900proceeds to block 912. For example, 908 may be performed by thedetermination component 1010 of FIG. 10. In the context of FIGS. 1 and3, for example, the UE 104/350 may compare the DMRS measurement to thechannel activity measured energy. In some aspects, the first UE maydetermine whether the amount of energy associated with the channelactivity exceeds the measurement of the DMRS within the channel activityby a predetermined threshold. The first UE may determine that thechannel activity corresponds to the downlink transmission associatedwith the second UE when the amount of energy associated with the channelactivity does not exceed the measurement of the DMRS within the channelactivity by the predetermined threshold. The first UE also may determinethat the channel activity does not correspond to the downlinktransmission associated with the second UE when the amount of energyassociated with the channel activity exceeds the measurement of the DMRSwithin the channel activity by the predetermined threshold.

At 910, the first UE may communicate, with the base station on thesecond subband, the uplink transmission when the channel activitycorresponds to the downlink transmission associated with the second UE.For example, 910 may be performed by transmission component 1006 of FIG.10. In the context of FIGS. 1 and 3, for example, the UE 104/350 maycommunicate the uplink transmission.

At 912, the first UE may refrain from transmitting the uplinktransmission on the second subband when the channel activity does notcorrespond to the downlink transmission associated with the second UE.In some aspects, the first UE may drop the uplink transmission. In otheraspects, the first UE may delay the transmission of the uplinktransmission until the communication medium is available (e.g., aftertransmission of the downlink transmission associated with the secondUE). In some aspects, the refraining is based on a configuration of thefirst UE. In other aspects, the refraining is based on an indicationincluded in the control information. For example, 912 may be performedby the transmission component 1006 of FIG. 10. In the context of FIGS. 1and 3, for example, the UE 104/350 may refrain from transmitting theuplink transmission.

FIG. 10 is a conceptual data flow diagram 1000 illustrating the dataflow between different means/components in an example apparatus 1002.The apparatus 1002 may be a UE or a component of a UE (e.g., such as UE104, 350). The apparatus 1002 may include a reception component 1004, atransmission component 1006, an LBT component 1008, and a determinationcomponent 1010.

The reception component 1004 may be configured to receive signals and/orother information from other devices including, e.g., base station 1050.The signals/information received by the reception component 1004 may beprovided to one or more components of the apparatus 1002 for furtherprocessing and use in performing various operations in accordance withthe methods discussed supra including the process 900. Thus, via thereception component 1004, the apparatus 1002 and/or one or morecomponents therein receive signals and/or other information (e.g., suchas data for the apparatus 1002, downlink control information, DMRSconfiguration and/or other control signaling) from the base station 1050as discussed supra and also discussed more specifically infra.

The transmission component 1006 may be configured to transmit variousmessages to one or more external devices, e.g., including the basestation 1050, in accordance with the methods disclosed herein. Themessages/signals to be transmitted may be generated by one or more othercomponents as discussed above, or the messages/signals to be transmittedmay be generated by the transmission component 1006 under thedirection/control of the one or more other components discussed supra.Thus, in various configurations, via the transmission component 1006,the apparatus 1002 and/or one or more components therein transmitsignals and/or other information (e.g., such as uplink communicationand/or other signals) to external devices such as the base station 1050.

In some implementations, the LBT component 1008 may be configured toobtain one or more measurements of a DMRS within channel activity on asecond subband of the unlicensed frequency band using an LBT operationbased on the DMRS configuration, e.g., as described in connection withblock 904 of FIG. 9. In some aspects, the LBT component 1008 maydetermine an amount of energy associated with the channel activity and ameasurement of the DMRS within the channel activity.

The determination component 1010 may be configured to determine whetherthe channel activity corresponds to the downlink transmission associatedwith the second UE based on the one or more measurements of the DMRSwithin the channel activity, e.g., as described in connection with block908 of FIG. 9. In some aspects, the determination component 1010 maydetermine whether the amount of energy associated with the channelactivity exceeds the measurement of the DMRS within the channel activityby a predetermined threshold. The determination component 1010 maydetermine that the channel activity corresponds to the downlinktransmission associated with the second UE when the amount of energyassociated with the channel activity does not exceed the measurement ofthe DMRS within the channel activity by the predetermined threshold. Thedetermination component 1010 also may determine that the channelactivity does not correspond to the downlink transmission associatedwith the second UE when the amount of energy associated with the channelactivity exceeds the measurement of the DMRS within the channel activityby the predetermined threshold.

The apparatus 1002 may include additional components that perform eachof the blocks of the algorithm in the aforementioned flowchart of FIG.9. As such, each block in the aforementioned flowchart of FIG. 9 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 11 is a diagram 1100 illustrating an example of a hardwareimplementation for an apparatus 1002′ employing a processing system1114. The processing system 1114 may be implemented with a busarchitecture, represented generally by the bus 1124. The bus 1124 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1114 and the overalldesign constraints. The bus 1124 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1104, the components 1004, 1006, 1008, 1010 and thecomputer-readable medium/memory 1122. The bus 1124 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 1114 may be coupled to a transceiver 1130. Thetransceiver 1130 is coupled to one or more antennas 1132. Thetransceiver 1130 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1130 receives asignal from the one or more antennas 1132, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1114, specifically the reception component 1004. Inaddition, the transceiver 1130 receives information from the processingsystem 1114, specifically the transmission component 1016, and based onthe received information, generates a signal to be applied to the one ormore antennas 1132. The processing system 1114 includes a processor 1120coupled to a computer-readable medium/memory 1122. The processor 1120 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1122. The software, whenexecuted by the processor 1120, causes the processing system 1114 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1122 may also be used forstoring data that is manipulated by the processor 1120 when executingsoftware. The processing system 1114 further includes at least one ofthe components 1004, 1006, 1008, 1010. The components may be softwarecomponents running in the processor 1120, resident/stored in thecomputer-readable medium/memory 1122, one or more hardware componentscoupled to the processor 1120, or some combination thereof. Theprocessing system 1114 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356, and the controller/processor 359. Alternatively, theprocessing system 1114 may be the entire UE (e.g., see 350 of FIG. 3).

In one configuration, the apparatus 1002/1002′ is a UE for wirelesscommunication including means for receiving, from a base station on afirst subband of an unlicensed frequency band, control informationcomprising a resource allocation of an uplink transmission associatedwith the first UE and a demodulation reference signal (DMRS)configuration of a downlink transmission associated with a second UE.The apparatus 1002/1002′ also includes means for obtaining one or moremeasurements of a DMRS within channel activity on a second subband ofthe unlicensed frequency band using a listen-before-talk (LBT) operationbased on the DMRS configuration. The apparatus 1002/1002′ also includesmeans for communicating, with the base station on the second subband,the uplink transmission when the channel activity corresponds to thedownlink transmission associated with the second UE based on the one ormore measurements of the DMRS within the channel activity.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1002 and/or the processing system 1114 ofthe apparatus 1002′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 1114 mayinclude the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, theaforementioned means may be the TX Processor 368, the RX Processor 356,and the controller/processor 359 configured to perform the functionsrecited by the aforementioned means.

FIG. 12 is a flow chart illustrating an example of a process 1200 forDMRS-assisted LBT for full-duplex wireless communications at a basestation, in accordance with various aspects of the present disclosure.The process 1200 may be performed by a base station or a component of abase station (e.g., the base station 102, 108, 310, which may includethe memory 360 and which may be the entire base station 310 or acomponent of the base station 310, such as the TX processor 368, the RXprocessor 356, and/or the controller/processor 359). According tovarious aspects, one or more of the illustrated operations of theprocess 1200 may be omitted, transposed, and/or contemporaneouslyperformed.

At 1202, the base station may generate control information comprising aresource allocation of an uplink transmission associated with a first UEand a DMRS configuration of a downlink transmission associated with asecond UE. For example, 1202 may be performed by reception component1304 of FIG. 13. In the context of FIGS. 1 and 3, for example, the BS102/180/310 may receive the uplink transmission.

At 1204, the base station may determine whether the downlinktransmission associated with the second UE overlaps a single uplinktransmission associated with the first UE or a plurality of uplinktransmissions associated with a plurality of UEs (including the firstUE). If the downlink transmission overlaps a single uplink transmission,then the process 1200 proceeds to block 1206. Otherwise, the process1200 proceeds to block 1208 when the downlink transmission overlaps witha plurality of uplink transmissions. For example, 1204 may be performedby determination component 1310 of FIG. 13. In the context of FIGS. 1and 3, for example, the BS 102/180/310 may determine whether thedownlink transmission overlaps a single uplink transmission or aplurality of uplink transmissions.

At 1206, the base station may select a first PDCCH of a plurality ofPDCCHs for transmission of the control information when the downlinktransmission associated with the second UE overlaps the uplinktransmission associated with the first UE. For example, 1206 may beperformed by selection component 1312 of FIG. 13. In the context ofFIGS. 1 and 3, for example, the BS 102/180/310 may select the firstPDCCH.

At 1208, the base station may select a first GC-PDCCH of a plurality ofGC-PDCCHs for transmission of the control information when the downlinktransmission associated with the second UE overlaps the plurality ofuplink transmissions associated with the first UE and a third UE. Forexample, 1208 may be performed by the selection component 1312 of FIG.13. In the context of FIGS. 1 and 3, for example, the BS 102/180/310 mayselect the first GC-PDCCH. In some aspects, the downlink transmissionassociated with the second UE may include a plurality of DMRS symboldurations. In this regard, the control information may include a firstDMRS configuration specifying a first DMRS symbol duration of theplurality of DMRS symbol durations during which the first UE may performa first LBT operation and a second DMRS symbol duration of the pluralityof DMRS symbol durations during which a third UE may perform a secondLBT operation.

At 1210, the base station may transmit, to the first UE on a firstsubband of an unlicensed frequency band, the control information. Forexample, 1210 may be performed by configuration component 1314 of FIG.13 through coordination with transmission component 1306 of FIG. 13. Inthe context of FIGS. 1 and 3, for example, the BS 102/180/310 maytransmit the control information.

At 1212, the base station may receive, from the first UE on the secondsubband, the uplink transmission based on the DMRS configuration and acorrespondence between channel activity on the second subband and thedownlink transmission associated with the second UE. For example, 1212may be performed by reception component 1304 of FIG. 13. In the contextof FIGS. 1 and 3, for example, the BS 102/180/310 may receive the uplinktransmission.

FIG. 13 is a conceptual data flow diagram 1300 illustrating the dataflow between different means/components in an example apparatus 1302.The apparatus 1302 may be a base station or a component of a basestation (e.g., such as BS 102/180, 310). The apparatus 1302 may includea reception component 1304, a transmission component 1306, a generationcomponent 1308, a determination component 1310, a selection component1312 and a configuration component 1314.

The reception component 1304 may be configured to receive signals and/orother information from other devices including, e.g., UE 1350. Thesignals/information received by the reception component 1304 may beprovided to one or more components of the apparatus 1302 for furtherprocessing and use in performing various operations in accordance withthe methods discussed supra including the process 1200. Thus, via thereception component 1304, the apparatus 1302 and/or one or morecomponents therein receive signals and/or other information (e.g., suchas uplink communication and/or other signals) from the UE 1350 asdiscussed supra and also discussed more specifically infra. In someimplementations, the reception component 1304 may be configured toreceive, from the first UE on the second subband, the uplinktransmission based on the DMRS configuration and a correspondencebetween channel activity on the second subband and the downlinktransmission associated with the second UE, e.g., as described inconnection with block 1212 of FIG. 12.

The transmission component 1306 may be configured to transmit variousmessages to one or more external devices, e.g., including the UE 1350,in accordance with the methods disclosed herein. The messages/signals tobe transmitted may be generated by one or more other components asdiscussed above, or the messages/signals to be transmitted may begenerated by the transmission component 1306 under the direction/controlof the one or more other components discussed supra. Thus, in variousconfigurations, via the transmission component 1306, the apparatus 1302and/or one or more components therein transmit signals and/or otherinformation (e.g., such as downlink control information, DMRSconfiguration signaling and/or other control signals) to externaldevices such as the UE 1350. In some implementations, the transmissioncomponent 1306 may be configured to transmit, to the first UE on a firstsubband of an unlicensed frequency band, the control information, e.g.,as described in connection with block 1210 of FIG. 12.

In some implementations, the generation component 1308 may be configuredto generate control information comprising a resource allocation of anuplink transmission associated with a first UE and a DMRS configurationof a downlink transmission associated with a second UE, e.g., asdescribed in connection with block 1202 of FIG. 12.

In some implementations, the determination component 1310 may beconfigured to determine whether the downlink transmission associatedwith the second UE overlaps a single uplink transmission associated withthe first UE or a plurality of uplink transmissions associated with aplurality of UEs (including the first UE), e.g., as described inconnection with block 1204 of FIG. 12.

In some implementations, the selection component 1312 may be configuredto select a first PDCCH of a plurality of PDCCHs for transmission of thecontrol information when the downlink transmission associated with thesecond UE overlaps the uplink transmission associated with the first UE,e.g., as described in connection with block 1206 of FIG. 12. In one ormore implementations, the selection component 1312 also may beconfigured to select a first GC-PDCCH of a plurality of GC-PDCCHs fortransmission of the control information when the downlink transmissionassociated with the second UE overlaps the plurality of uplinktransmissions associated with the first UE and a third UE, e.g., asdescribed in connection with block 1208 of FIG. 12.

In some implementations, the configuration component 1314 may beconfigured to transmit, to the first UE on a first subband of anunlicensed frequency band, the control information, e.g., as describedin connection with block 1210 of FIG. 12.

The apparatus 1302 may include additional components that perform eachof the blocks of the algorithm in the aforementioned flowchart of FIG.12. As such, each block in the aforementioned flowchart of FIG. 12 maybe performed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 14 is a diagram 1400 illustrating an example of a hardwareimplementation for an apparatus 1302′ employing a processing system1414. The processing system 1414 may be implemented with a busarchitecture, represented generally by the bus 1424. The bus 1424 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1414 and the overalldesign constraints. The bus 1424 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1404, the components 1304, 1306, 1308, 1310, 1312, 1314and the computer-readable medium/memory 1422. The bus 1424 may also linkvarious other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The processing system 1414 may be coupled to a transceiver 1430. Thetransceiver 1430 is coupled to one or more antennas 1432. Thetransceiver 1430 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1430 receives asignal from the one or more antennas 1432, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1414, specifically the reception component 1304. Inaddition, the transceiver 1430 receives information from the processingsystem 1414, specifically the transmission component 1306, and based onthe received information, generates a signal to be applied to the one ormore antennas 1432. The processing system 1414 includes a processor 1420coupled to a computer-readable medium/memory 1422. The processor 1420 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1422. The software, whenexecuted by the processor 1420, causes the processing system 1414 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1422 may also be used forstoring data that is manipulated by the processor 1420 when executingsoftware. The processing system 1414 further includes at least one ofthe components 1304, 1306, 1308, 1310, 1312, 1314. The components may besoftware components running in the processor 1420, resident/stored inthe computer-readable medium/memory 1422, one or more hardwarecomponents coupled to the processor 1420, or some combination thereof.The processing system 1414 may be a component of the BS 310 and mayinclude the memory 376 and/or at least one of the TX processor 316, theRX processor 370, and the controller/processor 375. Alternatively, theprocessing system 1414 may be the entire BS (e.g., see 310 of FIG. 3).

In one configuration, the apparatus 1302/1302′ is a UE for wirelesscommunication including means for generating control informationcomprising a resource allocation of an uplink transmission associatedwith a first UE and a DMRS configuration of a downlink transmissionassociated with a second UE. The apparatus 1302/1302′ also includesmeans for transmitting, to the first UE on a first subband of anunlicensed frequency band, the control information. The apparatus1302/1302′ also includes means for receiving, from the first UE on thesecond subband, the uplink transmission based on the DMRS configurationand a correspondence between channel activity on the second subband andthe downlink transmission associated with the second UE.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1302 and/or the processing system 1414 ofthe apparatus 1302′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 1414 mayinclude the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. An apparatus for wireless communication at afirst user equipment (UE), the apparatus comprising: at least oneprocessor; a transceiver; and a memory, coupled to the at least oneprocessor and the transceiver, storing instructions, which when executedby the at least one processor, cause the apparatus to: receive, from abase station on a first subband of an unlicensed frequency band, via thetransceiver, control information comprising a resource allocation of anuplink transmission associated with the first UE and a demodulationreference signal (DMRS) configuration of a downlink transmissionassociated with a second UE; obtain one or more measurements of a DMRSwithin channel activity on a second subband of the unlicensed frequencyband using a listen-before-talk (LBT) operation based on the DMRSconfiguration; and communicate, with the base station on the secondsubband, via the transceiver, the uplink transmission when the channelactivity corresponds to the downlink transmission associated with thesecond UE based on the one or more measurements of the DMRS within thechannel activity.
 2. The apparatus of claim 1, wherein the instructions,which when executed by the at least one processor, further cause theapparatus to refrain from transmitting the uplink transmission on thesecond subband when the channel activity does not correspond to thedownlink transmission associated with the second UE based on the one ormore measurements of the DMRS within the channel activity.
 3. Theapparatus of claim 1, wherein the obtaining the one or more measurementscomprises to determine an amount of energy associated with the channelactivity and a measurement of the DMRS within the channel activity. 4.The apparatus of claim 3, wherein the instructions, which when executedby the at least one processor, further cause the apparatus to: determinewhether the amount of energy associated with the channel activityexceeds the measurement of the DMRS within the channel activity by apredetermined threshold; determine that the channel activity correspondsto the downlink transmission associated with the second UE when theamount of energy associated with the channel activity does not exceedthe measurement of the DMRS within the channel activity by thepredetermined threshold; and determine that the channel activity doesnot correspond to the downlink transmission associated with the secondUE when the amount of energy associated with the channel activityexceeds the measurement of the DMRS within the channel activity by thepredetermined threshold.
 5. The apparatus of claim 1, wherein theinstructions, which when executed by the at least one processor, furthercause the apparatus to: determine that the uplink transmission isscheduled during a same time and frequency resource as the downlinktransmission associated with the second UE based on the resourceallocation and the DMRS configuration; and obtain information of theDMRS that indicates one or more of a location of the DMRS in time andfrequency, a precoder associated with the DMRS or a transmission powerof the DMRS in the downlink transmission.
 6. The apparatus of claim 1,wherein: the first subband comprises a plurality of group commonphysical downlink control channels (GC-PDCCHs), multiplexed in time orfrequency, and the receiving the control information comprises toreceive, from the base station in a first GC-PDCCH of the plurality ofGC-PDCCHs, via the transceiver, the control information.
 7. Theapparatus of claim 1, wherein: the second subband comprises a pluralityof physical uplink shared channels (PUSCHs), multiplexed in time orfrequency, and the communicating the uplink transmission comprises totransmit, to the base station in a first PUSCH of the plurality ofPUSCHs, via the transceiver, an uplink signal using resources includedin the resource allocation that at least partially overlap resources ofthe downlink transmission associated with the second UE.
 8. A method ofwireless communication at a first user equipment (UE), the methodcomprising: receiving, from a base station on a first subband of anunlicensed frequency band, control information comprising a resourceallocation of an uplink transmission associated with the first UE and ademodulation reference signal (DMRS) configuration of a downlinktransmission associated with a second UE; obtaining one or moremeasurements of a DMRS within channel activity on a second subband ofthe unlicensed frequency band using a listen-before-talk (LBT) operationbased on the DMRS configuration; and communicating, with the basestation on the second subband, the uplink transmission when the channelactivity corresponds to the downlink transmission associated with thesecond UE based on the one or more measurements of the DMRS within thechannel activity.
 9. The method of claim 8, further comprising:refraining from transmitting the uplink transmission on the secondsubband when the channel activity does not correspond to the downlinktransmission associated with the second UE based on the one or moremeasurements of the DMRS within the channel activity.
 10. The method ofclaim 9, wherein the refraining is based on a configuration of the firstUE.
 11. The method of claim 9, wherein the refraining is based on anindication included in the control information.
 12. The method of claim8, wherein the DMRS configuration comprises one or more of a location ofthe DMRS in time and frequency, a precoder associated with the DMRS, ora transmission power of the DMRS in the downlink transmission.
 13. Themethod of claim 8, wherein the control information comprises anindication of existence or non-existence of the downlink transmissionassociated with the second UE on at least partially overlappingresources of the uplink transmission associated with the first UE in oneor more of time or frequency.
 14. The method of claim 8, wherein theobtaining the one or more measurements comprises determining an amountof energy associated with the channel activity and a measurement of theDMRS within the channel activity.
 15. The method of claim 14, furthercomprising: determining whether the amount of energy associated with thechannel activity exceeds the measurement of the DMRS within the channelactivity by a predetermined threshold; determining that the channelactivity corresponds to the downlink transmission associated with thesecond UE when the amount of energy associated with the channel activitydoes not exceed the measurement of the DMRS within the channel activityby the predetermined threshold; and determining that the channelactivity does not correspond to the downlink transmission associatedwith the second UE when the amount of energy associated with the channelactivity exceeds the measurement of the DMRS within the channel activityby the predetermined threshold.
 16. The method of claim 8, furthercomprising: determining that the uplink transmission is scheduled duringa same time and frequency resource as the downlink transmissionassociated with the second UE based on the resource allocation and theDMRS configuration; and obtaining information of the DMRS that indicatesone or more of a location of the DMRS in time and frequency, a precoderassociated with the DMRS or a transmission power of the DMRS in thedownlink transmission.
 17. The method of claim 8, wherein: the firstsubband comprises a plurality of physical downlink control channels(PDCCHs), multiplexed in time or frequency, and the receiving thecontrol information comprises receiving, from the base station in afirst PDCCH of the plurality of PDCCHs, the control information.
 18. Themethod of claim 8, wherein: the first subband comprises a plurality ofgroup common physical downlink control channels (GC-PDCCHs), multiplexedin time or frequency, and the receiving the control informationcomprises receiving, from the base station in a first GC-PDCCH of theplurality of GC-PDCCHs, the control information.
 19. The method of claim18, wherein: the downlink transmission associated with the second UEcomprises a plurality of DMRS symbol durations, and the controlinformation comprises a first DMRS configuration specifying a first DMRSsymbol duration of the plurality of DMRS symbol durations during whichthe first UE performs a first listen-before-talk (LBT) operation and asecond DMRS symbol duration of the plurality of DMRS symbol durationsduring which a third UE performs a second LBT operation.
 20. The methodof claim 8, wherein: the second subband comprises a plurality ofphysical uplink shared channels (PUSCHs), multiplexed in time orfrequency, and the communicating the uplink transmission comprisestransmitting, to the base station in a first PUSCH of the plurality ofPUSCHs, an uplink signal using resources included in the resourceallocation that at least partially overlap resources of the downlinktransmission associated with the second UE.
 21. An apparatus forwireless communication at a base station, the apparatus comprising: atleast one processor; a transceiver; and a memory, coupled to the atleast one processor and the transceiver, storing instructions, whichwhen executed by the at least one processor, cause the apparatus to:generate control information comprising a resource allocation of anuplink transmission associated with a first user equipment (UE) and ademodulation reference signal (DMRS) configuration of a downlinktransmission associated with a second UE; transmit, to the first UE on afirst subband of an unlicensed frequency band, via the transceiver, thecontrol information; and receive, from the first UE on the secondsubband, via the transceiver, the uplink transmission based on the DMRSconfiguration and a correspondence between channel activity on thesecond subband and the downlink transmission associated with the secondUE.
 22. The apparatus of claim 21, wherein: the first subband comprisesa plurality of physical downlink control channels (PDCCHs), multiplexedin time or frequency, the transmitting the control information comprisesto transmit, to the first UE in a first PDCCH of the plurality ofPDCCHs, the control information, and the instructions, which whenexecuted by the at least one processor, further cause the apparatus to:determine whether the downlink transmission associated with the secondUE overlaps the uplink transmission associated with the first UE; andselect the first PDCCH of the plurality of PDCCHs for transmission ofthe control information when the downlink transmission associated withthe second UE overlaps the uplink transmission associated with the firstUE.
 23. The apparatus of claim 21, wherein: the first subband comprisesa plurality of group common physical downlink control channels(GC-PDCCHs), multiplexed in time or frequency, and the transmitting thecontrol information comprises to transmit, to the first UE in a firstGC-PDCCH of the plurality of GC-PDCCHs, via the transceiver, the controlinformation, the instructions, which when executed by the at least oneprocessor, further cause the apparatus to: determine whether thedownlink transmission associated with the second UE overlaps a pluralityof uplink transmissions associated with a plurality of UEs; and selectthe first GC-PDCCH of the plurality of GC-PDCCHs for transmission of thecontrol information when the downlink transmission associated with thesecond UE overlaps the plurality of uplink transmissions associated withthe first UE and a third UE.
 24. The apparatus of claim 23, wherein: thedownlink transmission associated with the second UE comprises aplurality of DMRS symbol durations, and the control informationcomprises a first DMRS configuration specifying a first DMRS symbolduration of the plurality of DMRS symbol durations during which thefirst UE performs a first listen-before-talk (LBT) operation and asecond DMRS symbol duration of the plurality of DMRS symbol durationsduring which the third UE performs a second LBT operation.
 25. A methodof wireless communication at a base station (BS), the method comprising:generating control information comprising a resource allocation of anuplink transmission associated with a first user equipment (UE) and ademodulation reference signal (DMRS) configuration of a downlinktransmission associated with a second UE; transmitting, to the first UEon a first subband of an unlicensed frequency band, the controlinformation; and receiving, from the first UE on the second subband, theuplink transmission based on the DMRS configuration and a correspondencebetween channel activity on the second subband and the downlinktransmission associated with the second UE.
 26. The method of claim 25,wherein: the first subband comprises a plurality of physical downlinkcontrol channels (PDCCHs), multiplexed in time or frequency, and thetransmitting the control information comprises transmitting, to thefirst UE in a first PDCCH of the plurality of PDCCHs, the controlinformation.
 27. The method of claim 26, further comprising: determiningwhether the downlink transmission associated with the second UE overlapsthe uplink transmission associated with the first UE; and selecting thefirst PDCCH of the plurality of PDCCHs for transmission of the controlinformation when the downlink transmission associated with the second UEoverlaps the uplink transmission associated with the first UE.
 28. Themethod of claim 25, wherein: the first subband comprises a plurality ofgroup common physical downlink control channels (GC-PDCCHs), multiplexedin time or frequency, and the transmitting the control informationcomprises transmitting, to the first UE in a first GC-PDCCH of theplurality of GC-PDCCHs, the control information.
 29. The method of claim28, further comprising: determining whether the downlink transmissionassociated with the second UE overlaps a plurality of uplinktransmissions associated with a plurality of UEs; and selecting thefirst GC-PDCCH of the plurality of GC-PDCCHs for transmission of thecontrol information when the downlink transmission associated with thesecond UE overlaps the plurality of uplink transmissions associated withthe first UE and a third UE.
 30. The method of claim 29, wherein: thedownlink transmission associated with the second UE comprises aplurality of DMRS symbol durations, and the control informationcomprises a first DMRS configuration specifying a first DMRS symbolduration of the plurality of DMRS symbol durations during which thefirst UE performs a first listen-before-talk (LBT) operation and asecond DMRS symbol duration of the plurality of DMRS symbol durationsduring which the third UE performs a second LBT operation.